Liquid Chromatograph Solvent Delivery Coordination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In liquid chromatography systems, the pre-injector dwell volume introduces a significant delay in solvent stream delivery to the injector valve, which becomes problematic when chromatographic run times are short, as it can account for a substantial percentage of the total run time.

Innovation Solution

The solvent delivery system starts delivering the solvent stream in parallel with the autosampler's pre-injection operations, coordinating the timing to ensure the solvent stream arrives at the injector valve approximately when the autosampler completes its pre-injection sequence, thereby reducing the dead time introduced by the pre-injector dwell volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the pump delivers the solvent stream sequentially after the autosampler completes pre-injection operations, then the injection process is simple to control, but the pre-injector dwell volume introduces significant delay to the start of each injection

Engineering Contradiction:

Improveinjection delay timeVSAvoidcoordination system complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The pump starts delivering the solvent stream in advance before the autosampler completes its pre-injection operations. The system calculates the pre-injector dwell volume and flow rate to determine the optimal start time, so the solvent stream is already in the tubing when the sample is ready for injection, eliminating the delay caused by the dwell volume.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses a coordinated control mechanism where the autosampler and pump communicate their operational status and timing. The autosampler notifies the pump of its pre-injection completion status, and the pump adjusts its solvent delivery timing based on this feedback to achieve precise synchronization.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the pre-injector dwell volume is large (hundreds of microliters), then the solvent mixing is more thorough, but the delay to the start of each injection increases significantly

Engineering Contradiction:

Improvesolvent mixture stabilityVSAvoidinjection start delay

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The solvent stream is delivered in advance during the pre-injection period, allowing the large dwell volume to be filled with properly mixed solvent before the sample injection begins. This eliminates the delay while maintaining the benefit of thorough mixing that occurs during the pre-injection operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pump delivers the solvent stream continuously without interruption, starting before pre-injection operations and continuing through the injection event. This continuous flow ensures that the large dwell volume does not create delays, as the solvent is already in motion and reaching the injector throughout the entire process.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If the pump starts solvent stream delivery before pre-injection operations complete, then the overall run time is reduced, but coordination between pump and autosampler becomes more complex

Engineering Contradiction:

Improvechromatographic throughputVSAvoidpump-autosampler coordination

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system implements a feedback-based coordination mechanism where the autosampler communicates its operational state to the pump, and the pump adjusts its solvent delivery timing accordingly. This allows the pump to start delivering solvent before pre-injection operations complete while maintaining precise control over the injection timing.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system calculates the pre-injector dwell volume and flow rate in advance to determine the optimal timing for starting solvent delivery. This preliminary calculation allows the pump and autosampler to be coordinated without complex real-time control, as the timing is predetermined based on system parameters.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9519291B2Coordination of solvent delivery with pre-injection operations in a liquid chromatograph

Publication Date: 2016.12.13 WATERS TECHNOLOGY CORP

AI summary

A liquid chromatography system includes an autosampler that prepares a sample for introduction to a solvent stream and a solvent delivery system that delivers a solvent stream to the autosampler. Delivery of the solvent stream occurs in parallel with the autosampler's pre-injection operations. The autosampler starts pre-injection operations to make the sample ready for injection into the mixture stream, and the solvent delivery system starts delivery of a solvent stream to the autosampler. The start of the solvent stream delivery is coordinated with the start of the pre-injection operations such that the solvent stream arrives at the autosampler approximately coincident with when the autosampler completes the pre-injection operations, making the sample ready for injection.